X-ray photoelectron spectrometry

Dynamic SIMS is used to measure elemental impurities in a wide variety of materials, but is almost new used to provide chemical bonding and molecular information because of the destructive nature of the technique. Molecular identihcation or measurement of the chemical bonds present in the sample is better performed using analytical techniques, such as X-Ray Photoelectron Spectrometry (XPS), Infrared (IR) Spectroscopy, or Static SIMS. 

One other technique has become central in surface research this is X-ray photoelectron spectrometry, earlier known as ESCA, electron spectroscopy for chemical analysis . Photoelectrons are emitted from a surface irradiated by X-rays. The precautions which have to be taken to ensure accurate quantitative analysis by this much-used technique are set out by Seah (1980). 

Charge distributions and bonding in compounds of Cd and Hg in the solid and gaseous states can be studied by the well-established X-ray photoelectron spectrometry (XPS) and ultraviolet photoelectron spectrometry (UPS), respectively. With XPS, inner-shell electrons are removed which are indirectly influenced by the bonding, i.e., distribution of the valence electrons. UPS sees this electron distribution directly, since it measures the residual kinetic energies of electrons removed from the valence shells of the atoms, or, better, from the outer occupied orbitals of the molecules. The most detailed information accessible by UPS is obtained on gases, and it is thus applied here to volatile compounds, i.e., to the halides mainly of Hg and to organometallic compounds. 

As mentioned already, many surface-analysis techniques are available nowadays. In the opinion of some specialists in this field [36, 37], four of these are greater in importance X-ray photoelectron spectrometry (ESCA), Auger electron spectrometry (AES), secondary-ion mass spectrometry (SIMS), and low-energy ion scattering spectrometry (ISS). 

X-Ray Photoelectron Spectrometry. X-ray photoelectron spectrometry (XPS) was applied to analyses of the surface composition of polymer-stabilized metal nanoparticles, which was mentioned in the previous section. This is true in the case of bimetallic nanoparticles as well. In addition, the XPS data can support the structural analyses proposed by EXAFS, which often have considerably wide errors. Quantitative XPS data analyses can be carried out by using an intensity factor of each element. Since the photoelectron emitted by x-ray irradiation is measured in XPS, elements located near the surface can preferentially be detected. The quantitative analysis data of PVP-stabilized bimetallic nanoparticles at a 1/1 (mol/mol) ratio are collected in Table 9.1.1. For example, the composition of Pd and Pt near the surface of PVP-stabilized Pd/Pt bimetallic nanoparticles is calculated to be Pd/Pt = 2.06/1 (mol/ mol) by XPS as shown in Table 9.1.1, while the metal composition charged for the preparation is 1/1. Thus, Pd is preferentially detected, suggesting the Pd-shell structure. This result supports the Pt-core/Pd-shell structure. The similar consideration results in the Au-core/Pd-shell and Au-core/Pt-shell structure for PVP-stabilized Au/Pd and Au/Pt bimetallic nanoparticles, respectively (53). 

Ion scattering spectrometry (ISS) Secondary ion mass spectrometry (SIMS) Auger electron spectrometry (AES) X-ray photoelectron spectrometry (XPS)... 

In certain applications (e.g., X-ray photoelectron spectrometry) an electron beam must be analyzed by its kinetic energy using a 180° hemispherical energy analyzer consisting of two concentric hemispheres coupled to a wide-area charge-coupled detector (see Fig. 10.29). 

WD-XRF wavelength dispersive-X-ray emission spectrometrywhich is visible microscopically siderosis deposition of iron in tissues and organs WHO World Health Organisation widy sign a dark pigment precipitation in hair roots at the fourth or fifth day after the intake of a toxic dose of thallium Wilson s disease recessive autosomal, hereditary disease (if untreated, results in invalidity and death) in which toxic amounts of copper are accumulated in the liver and central nervous system XPS X-ray photoelectron spectrometry XRF X-ray fluorescence spectrometry... 

Quantitative X-ray photoelectron spectrometry has become more popular in... 

X-ray photoelectron spectrometry (XPS) is used to determine major and minor element compositions of metallic and ceramic surfaces. It can also be used to determine the oxidation states of ions on the surface of a sample. However, it has a limited depth penetration of 2-20 atomic layers and so the measurements taken will be greatly influenced by the method of sample preparation. The ability to characterize elements with atomic numbers less than 10, coupled with the ability to analyze samples smaller than 1.5 cm, make this technique particularly useful for the colorants and clarifying agents used in glasses and ceramics. For example, it has been used to... 

Figure 5 Some analytical techniques for the investigation of atomization mechanisms. MAS, molecular absorption spectrometry MS, mass spectrometry XRD, X-ray diffraction XRPS, X-ray photoelectron spectrometry RBS, Rutherford backscattering spectrometry SEM, scanning electron microscopy SIMS, secondary ion mass spectrometry.

Abbreviations AES, Auger emission spectrometry CRM, Certified reference material DL, Detection limit ED, Energy dispersive ESRF, European Synchrotron Radiation Facility EXAES, Extended X-ray absorption fine structure NEXAFS, Near edge X-ray absorption fine structure PCI, Phase contrast imaging RM, Reference material SR, Synchrotron radiation SRM, Standard reference material TXRF, Total reflection X-ray fluorescence XANES, X-ray absorption near edge structure XAS, X-ray absorption spectrometry XDM, X-ray diffraction microscopy XFCT, X-ray fluorescence computerized microtomography XPEEM, X-ray photoelectron microscopy XPS, X-ray photoelectron spectrometry XRD, X-ray diffraction XRF, X-ray fluorescence... 

The surface comi>osition of the powder was determined by X-ray photoelectron spectrometry (XPS). In addition to the expected major constituents of the powder (silicon, nitrogen, and oxygen), carbon and fluorine are also present on the surface. Chlorine, iron, calcium and aluminum, although present in greater amounts than fluorine in the bulk sample, were not detected on the surface in measurable quantities. 

BH2 NH2-)n oligomers with n>5 have been studied by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) [30], as well as by mass spectrometry and X-ray photoelectron spectrometry. The results have been interpreted in terms of a large cyclic structure of poly(aminoborane) [31]. 

Surface analysis such as dynamic contact angle and surface tension are used to ensure proper wetting of epoxy and the substrate. Microscopic techniques, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), are widely used to study morphology, fracture, and adhesion issues of cured epoxy systems. Chemical analysis techniques, such as micro-IR, X-ray photoelectron spectrometry (XPS), and secondary ion mass... 

Quantitative X-ray photoelectron spectrometry has become more popular in recent years. The factors relating the intensity of emission to atomic concentration (density) are given in Equation 21-3. 

The techniques mentioned so far provide no direct spatially resolved information on the chemical composition of materials. Various established analytical techniques, such as secondary-ion mass spectrometry (SIMS), X-ray photoelectron spectrometry (XPS), and infrared (IR) and Raman microspectrometry, can be used to carry out local compositional studies. In the case of SIMS and XPS, the sample needs to be held in high vacuum, while in IR and Raman microspectrometry, the resolution is limited by the relatively large wavelength... 

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